Make javatemplates work with other plugins

package org.apache.struts2.views.java;

import org.apache.struts2.StrutsException;
import org.apache.struts2.components.template.BaseTemplateEngine;
import org.apache.struts2.components.template.Template;
import org.apache.struts2.components.template.TemplateEngine;
import org.apache.struts2.components.template.TemplateEngineManager;
import org.apache.struts2.components.template.TemplateRenderingContext;
import org.apache.struts2.views.java.simple.SimpleTheme;

import java.util.HashMap;
import java.util.StringTokenizer;

import com.opensymphony.xwork2.util.logging.LoggerFactory;
import com.opensymphony.xwork2.util.logging.Logger;
import com.opensymphony.xwork2.util.ClassLoaderUtil;
import com.opensymphony.xwork2.config.ConfigurationException;
import com.opensymphony.xwork2.inject.Inject;

/**
 * Template engine that renders tags using java implementations
 */
public class JavaTemplateEngine extends BaseTemplateEngine {

	private static final Logger LOG = LoggerFactory
			.getLogger(JavaTemplateEngine.class);

	// The struts template engine manager
	protected TemplateEngineManager templateEngineManager;

	// The struts default template type. If struts ever changes this will need
	// updating.
	private String defaultTemplateType = "ftl";

	@Inject
	public void setTemplateEngineManager(TemplateEngineManager mgr) {
		this.templateEngineManager = mgr;
	}

	private Themes themes = new Themes() {
		{
			add(new SimpleTheme());
		}
	};

	@Override
	protected String getSuffix() {
		return "java";
	}

	public void renderTemplate(TemplateRenderingContext templateContext)
			throws Exception {

		Template t = templateContext.getTemplate();
		Theme theme = themes.get(t.getTheme());
		if (theme == null) {

			// Theme not supported, so do what struts would have done if we were
			// not here.
			if (LOG.isDebugEnabled()) {
				LOG.debug("Theme not found " + t.getTheme()
						+ "trying default templete engine using template type "
						+ defaultTemplateType);
			}

			final TemplateEngine engine = templateEngineManager
					.getTemplateEngine(templateContext.getTemplate(),
							defaultTemplateType);

			if (engine == null) {
				// May be the default template has changed?
				throw new ConfigurationException(
						"Unable to find a TemplateEngine for template type '"
								+ defaultTemplateType
								+ "' whilst trying to render template "
								+ templateContext.getTemplate());
			} else {

				try {
					// Retry render
					engine.renderTemplate(templateContext);
				} catch (Exception e) {
					// Give up and throw a new StrutsException(e);
					throw new StrutsException("Cannot render tag ["
							+ t.getName() + "] because theme [" + t.getTheme()
							+ "] was not found.");
				}

			}

		} else {
			// Render our template
			theme.renderTag(t.getName(), templateContext);
		}

	}

	private class Themes {
		private HashMap<String, Theme> themes = new HashMap<String, Theme>();

		public void add(Theme theme) {
			themes.put(theme.getName(), theme);
		}

		public Theme get(String name) {
			return themes.get(name);
		}
	}

	/**
	 * Allows for providing custom theme classes (implementations of the
	 * org.apache.struts2.views.java.Theme) interface for custom rendering of
	 * tags using the javatemplates engine
	 * 
	 * @param themeClasses
	 *            a comma delimited list of custom theme class names
	 */
	@Inject(value = "struts.javatemplates.customThemes", required = false)
	public void setThemeClasses(String themeClasses) {

		StringTokenizer customThemes = new StringTokenizer(themeClasses, ",");

		while (customThemes.hasMoreTokens()) {
			String themeClass = customThemes.nextToken().trim();
			try {
				if (LOG.isInfoEnabled()) {
					LOG.info("Registering custom theme '" + themeClass
							+ "' to javatemplates engine");
				}

				// FIXME: This means Themes must have no-arg constructor -
				// should use object factory here
				// ObjectFactory.getObjectFactory().buildBean(ClassLoaderUtil.loadClass(themeClass,
				// getClass()), null);
				themes.add((Theme) ClassLoaderUtil.loadClass(themeClass,
						getClass()).newInstance());

			} catch (ClassCastException cce) {
				LOG.error("Invalid java them class '"
						+ themeClass
						+ "'. Class does not implement 'org.apache.struts2.views.java.Theme' interface");
			} catch (ClassNotFoundException cnf) {
				LOG.error("Invalid java theme class '" + themeClass
						+ "'. Class not found");
			} catch (Exception e) {
				LOG.error("Could not find messages file " + themeClass
						+ ".properties. Skipping");
			}
		}
	}

	/**
	 * Allows for providing an alternative default struts theme. Will default to
	 * "ftl" otherwise.
	 * 
	 * @param defaultTemplateTheme
	 *            the struts default theme
	 */
	@Inject(value = "struts.javatemplates.defaultTemplateType", required = false)
	public void setDefaultTemplateType(String type) {

		// Make sure we don't set ourself as default for race condition
		if (type != null && !type.equalsIgnoreCase(getSuffix())) {
			this.defaultTemplateType = type.toLowerCase();
		} else {
			LOG.error("Invalid struts.javatemplates.defaultTemplateType value.  Cannot be "
					+ getSuffix());
		}

	}
}